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Comment by bws99 | Hacker News Reader

Not seeing domestic cats on this list, though I suppose they only have murderous intentions and are too fluffy to actually execute on them.

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Cats carry Toxoplasma gondii, which is estimated to cause 750 deaths each year in the US alone. Around the world it's probably many times that number -- making Felis domesticus responsible (albeit indirectly) for more deaths than lions, elephants, hippopotamuses, and crocodiles combined.

Yup, which humans can pick up if they train their cat to use the same toilet as they do. Incredibly unsanitary. People and animals have separate shit receptacles for a reason.

It also influences human behaviour [1] which is probably why the grandparent's post is so massively downvoted ;)

It can also be deadly when it doesn't kill you "The difference in seroprevalence of toxoplasmosis in these 2 samples suggests that Toxoplasma-infected subjects have a 2.65 times higher risk of traffic accidents than Toxoplasma-free subjects"

EDIT: it also suggests an explanation: "the effects of T. gondii are best explained in evolutionary terms by the manipulation hypothesis, ie, the parasite changes the behavior of the rodent in such a way as to increase the chances of the parasite's getting into a feline and completing its life cycle."

[1] http://schizophreniabulletin.oxfordjournals.org/content/33/3...

Yep, cat people hate when you talk about their beloved pets. I've seen friends parents not wash their hands after playing with cats, after I suggest that they should they think I'm crazy for saying the phrase "brain parasite", even after showing wikipedia articles and suggesting that they look it up themselves.

Crazy cat ladies are undoubtedly infected with the parasite.

There needs to be more public awareness about this. Change your cat's litter-box daily, wash your hands after touching a cat (kittens specifically), be very cautious of outdoor cats, never handle a cat while pregnant or if you have a compromised immune system. Also wash vegetables and cook meat thoroughly.

Even more shocking is the percentage of the human population that is infected, over 30%!

In case you're wondering, I downvoted you for (a) getting needlessly personal and (b) more importantly, wildly overstating the very minor role of cats in spreading toxoplasma, relative to unwashed vegetables and undercooked meat. See http://en.wikipedia.org/wiki/Toxoplasma_gondii#Risk_factors_...: "Numerous studies have shown living in a household with a cat is not a significant risk factor for T. gondii infection, though living with several kittens has some significance."

It's fine if you don't like cats, but don't try to turn it into a moral crusade.

Oh, yeah: the research that suggests a connection between toxoplasma and feelings about cats shows that it makes men like cats more and women like them less. Your "crazy cat lady" thing has no basis in fact.

What about this? http://www.cdc.gov/parasites/toxoplasmosis/epi.html

Animal-to-human (zoonotic) transmission section: "Cats play an important role in the spread of toxoplasmosis"

"Because T. gondii can sexually reproduce only within cats, they are defined as the definitive host of T. gondii." No cats, no toxoplasma gondii brain parasite.

I have nothing against cats, but the phrase "brain parasite" and the fact that 30+% of the worlds human population are infected scares the shit out of me.

"As of 2013, at least 38 studies have found a positive correlation between T. gondii antibody titers and schizophrenia."

http://en.wikipedia.org/wiki/Toxoplasmosis#Schizophrenia

http://en.wikipedia.org/wiki/Crazy_Cat_Lady_Syndrome#Society...

That's it, I'm getting rid of my pet cat in favor of a hippopotamus. Safety first.

I bet that'd also significantly reduce your risk of burglary or home invasion.

I'd be willing to bet that pet hippopotamuses are more likely to kill their owners than pet cats.

http://abcnews.go.com/blogs/technology/2011/11/pet-hippo-kil...

Hippos are very aggressive and territorial. Also, they are surprisingly fast, especially in water. Many wild animals, even predators, won't move towards you unless you come real close. Hippos move towards you even if you just pass by the waterline of the sea that they are in.

Also, Hippos don't kill by biting you. They drown you by dragging you underwater - it's not that they misjudge their force.

Another problem is that they come out at night and like warm underground - streets for example. When I was in Africa last time, there was a horrible street accident with 17 dead as a pickup hit a hippo standing on the road at night. Grey, behind a corner -> bang.

What makes Hippos so dangerous to humans is they we are misjudging them as tame, slow creatures that mind their own thing.

Reminds me of: https://xkcd.com/795/

The vast, vast majority of toxoplasma occurs in 3rd world countries, and living with a cat has been shown not to increase chance of catching it at all.

Wiki:

The following have been identified as being risk factors for T. gondii infection:Exposure to or consumption of raw or undercooked meat[18][39][40][41]Drinking unpasteurized goat milk[39]Contact with soil[7][40]Eating unwashed raw vegetables or fruits[18]Cleaning cat litter boxes[18]Sewage has been identified as a carriage medium for the organism.[42][43][44][45]Numerous studies have shown living in a household with a cat is not a significant risk factor for T. gondiiinfection,[18][40][46] though living with several kittens has some significance.[47]

While that's technically true (some countries have numbers as high as 80% infection rates), over 16% of the US human population is infected. That's a very large amount when talking about a brain parasite.

http://www.cdc.gov/parasites/toxoplasmosis/

An adult cat might not have a high risk of spreading the parasite but a kitten is a major risk of infection and dropping the parasites in the owners home.

"vast majority of toxoplasma occurs in 3rd world countries"

Doesn't that hold for everything that happens to anyone, simply because much, much more people live in 3rd world countries?

I seem to have read that 70% of french people are infected, because they like raw meat so much.

> vast, vast majority of toxoplasma occurs in 3rd world countries

Well. I'm in France, which has a seriously high rate of infection; something around 50%.

>living with a cat has been shown not to increase chance of catching it at all.

But what's in the list of risk factors just below that?

> Contact with soil ... Cleaning cat litter boxes

So, living with a cat is fine as long as someone else changes its litter box, and you stay away from any soil into which your cat might potentially defecate.

You should have done more looking up about toxoplasmosis before starting this subthread. Toxoplasmosis is mostly a food-borne illness, worldwide, and especially in the United States is spread mostly by undercooked food.[1] In any event, the great majority of people infected with this parasite have no symptoms from the infection. (This is true of many infectious diseases; human beings have a well adapted immune system with a deep evolutionary history now that we and our ancestors have been living for millions of years in a world filled with other organisms. Malaria deserves special attention because the parasite is especially harmful to human beings.)

[1] http://www.cdc.gov/parasites/toxoplasmosis/epi.html

Food-borne, yes; but doesn't Toxoplasma gondii need to pass through a cat before it gets into the food?

Interestingly, cats are responsible for toxoplasmosis and it could be fatal in some cases. They also may carry rabies. I am pretty sure cats killed more people than sharks.

They're plotting: http://theoatmeal.com/misc/frame/cat_kill

They are still in planing phase, keep vigilant.

I guess they are busy with their plans for destroying the Earth: http://www.buzzfeed.com/smbc/cat-photo-industry

What surprised me most is learning that there is a creature which is capable of killing more humans than humans themselves.

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